Control moment gyroscope arrays, reaction wheel arrays, and other such deployed onboard spacecraft for attitude adjustment purposes generate vibratory forces during operation. Vibration isolation systems may be deployed between such attitude adjustment payloads and the spacecraft body to minimize the transmission of vibratory forces to the spacecraft body and any vibration-sensitive components (e.g., optical payloads) carried thereby. A typical vibration isolation system includes a number of individual vibrations isolators (typically three to eight isolators), which are positioned between the spacecraft payload and the spacecraft body in a multi-point mounting arrangement. The performance of a vibration isolation system is largely determined by the number of isolators included within the system, the manner in which the isolators are arranged, and the vibration attenuation characteristics of each individual isolator. In the case of passive damping systems, vibration isolation system employing three parameter isolators, which behave mechanically as a primary spring in parallel with a series-coupled secondary spring and damper, typically provide superior attenuation of high frequency vibratory forces (commonly referred to as “jitter”) as compared to vibration isolation systems employing other types of isolators (e.g., viscoelastic isolators).
In addition to producing vibrations, attitude adjustment payloads also tend to produce excessive amounts of heat during operation due, at least in part, to frictional forces at rotary interfaces and thermal inefficiencies inherent in electronics. If not adequately dissipated, the excess heat generated by a spacecraft payload can decrease the lifespan of hardware, increase the ambient temperature range to undesirable levels, and, in severe cases, result in equipment failure. A limited amount of excess heat may be removed from a payload by radiation; however, radiative heat transfer is generally inadequate to provide sufficient dissipation of heat in the case of payloads, such as larger control moment gyroscope arrays and reaction wheels arrays, having a relatively large thermal output. While radiative heat transfer can be improved by increasing the cumulative surface area of spacecraft-mounted parts in view of the heated payload surfaces (referred to as the “radiative view factor”), such a practice adds undesirable weight and bulk to the spacecraft and may still fail to provide adequate heat dissipation.
Heat straps may be utilized in conjunction with a vibration isolation system to provide supplemental, efficient heat transfer paths from the spacecraft payload to the spacecraft body. Heat straps commonly assume the form of highly-conductive, flexible metal strips or wire braids connected between the spacecraft payload and the spacecraft body. In general, the thermal conductivity of a heat strap is proportional to heat strap's cross-sectional area. Thus, as a spacecraft payload requires the removal of larger quantities of heat, the cross-sectional dimensions of the heat straps can be enlarged to provide the desired thermal capacity. However, as the dimensions of a heat strap increase, so too do the weight and stiffness of the heat strap. While providing excellent thermal conduction paths for payload heat dissipation, heat straps having larger cross-sectional areas tend to be undesirably bulky and weighty for deployed onboard a spacecraft. More importantly, heat straps having larger cross-sectional areas tend to be relatively stiff and may shunt vibratory forces around the vibrational isolators directly to the spacecraft body thereby partially defeating the effectiveness of the vibrational isolation system.
It would thus be desirable to provide embodiments of a relatively lightweight, compact, and low cost vibration isolator that provides effective attenuation of vibrations, while also providing an efficient thermal path for dissipating heat from a spacecraft payload to a host spacecraft. It would also be desirable to provide embodiments of a spacecraft isolation system employing a plurality of thermally-conductive vibration isolators. Other desirable features and characteristics of embodiments of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying drawings and the foregoing Background.